Dnmt3b expression prolongs leukemia latency. (A) Bone marrow from tetracycline-inducible Dnmt3b overexpressing mice was retrovirally transduced with MSCV-Myc-IRES-Bcl2-IRES-mCherry or MSCV-MLL-AF9-IRES-GFP oncogene vectors. Transduced cells were sorted for mCherry or GFP, respectively, and transplanted into sublethally irradiated recipient mice. Leukemia development was analyzed under conditions of high vs low DNA methylation. (B) Doxycycline-regulated Dnmt3b expression in sorted Myc-Bcl2 leukemic spleen cells from primary recipient mice of Dnmt3b-knock-in cells. Spleen cells were isolated from diseased mice and cultured in the presence of 1 µg/mL doxycycline, and protein expression was analyzed after different time points of addition and subsequent withdrawal of doxycycline by western blot. Spleen weight (C) and white blood cell (WBC) count (D) in primary recipients of Myc-Bcl2 leukemic Dnmt3b-knock-in cells at end of experiment. Each dot represents 1 leukemic mouse. **P < .01. (E) Percentage of leukemic (mCherry⁺) and nonleukemic (mCherry⁻) cells in bone marrow of primary recipient mice at end of experiment. Mean ± SD are shown (n = 5-9 mice). ****P < .0001. (F) Survival of primary recipients of Myc-Bcl2 leukemic wild-type and Dnmt3b-knock-in cells (n = 15 mice for each group). Dnmt3b expression was induced at time of transplantation. P < .001. (G) Survival of secondary recipients of Myc-Bcl2 leukemias (n = 15 mice for each group). P < .01.